The genetics revolution currently occurring in the scientific arena is creating new paradigms in the understanding of the biological function of genes and elucidating their role in human disease. These types of studies are beneficial since they are likely to produce new diagnostic tests and treatments for human disease. The genesis of mutant mice is an important component of the strategy employed in establishing gene function and their role in human disease. Consequently, the number of mutant mice being generated by the international scientific community is increasing at an exponential rate and current methods of storing these mice in repositories are not ideal in terms of costs and practicality. One possible solution may be the cryopreservation of mouse sperm but current methodologies are sub-optimal and inconsistent. This proposal aims to: (1) devise optimal methods of ejaculating mouse sperm from wild-type and well-characterized strains of transgenic, gene knockout and ENU-mutagenized mice previously generated and studied by these investigators; (2) optimized/or develop new methods of cryopreservation of mouse sperm from strains of mice as mentioned in (1); (3) use the above methods in conjunction with intrauterine or oviductal insemination and/or in vitro fertilization methodologies and/or intracytoplasmic sperm injection so as to attain the highest possible rates of liveborn pups; and (4) evaluate the normality of liveborn mice from (3) using immunophenotyping; histopathology; behavioural gene expression (using microarray and/or SAGE analysis) techniques.